Device for pumping viscous liquids through a bunghole of a drum



Oct. 15, 1968 M. s. BERMAN DEVICE FOR PUMPING VISCOUS LIQUIDS THROUGH A BUNGHOLE OF A DRUM.

Filed April 24, 1967 3 Sheets-Sheet FIG. .1

M720 8. BER/V4 Ivan/2y:

1968 M. s. BERMAN 3,405,643

DEVICE FOR PUMPING VISCOUS LIQUIDS THROUGH A BUNGHOLE OF A DRUM Filed April 24. 1967 5 Sheets-Sheet 2 x56 FIE! E 224 62 232 /54 MYRO/V 5. 8221 14 X/ M M flrrazvars Oct. 15, 1968 M s. BERMAN 3,405,643

DEVICE FOR PUMPI NG VISCOUS LIQUIDS THROUGH A BUNGHOLE OF A DRUM Filed April 24, 1967 5 Sheets-Sheet 5 FIG. 5" 224% af 3a INVENTOR. MYka 5. 352614 United States Patent 3,405,643 1 DEVICE FOR PUMPING VISCOUS LIQUIDS THROUGH A BUNGHOLE OF A DRUM Myron S. Ber-man, Minneapolis, Minn., assiguor to Raleigh Industries, Inc., Minneapolis, Minn., a corporation of Minnesota Filed Apr. 24, 1967, Ser. No. 633,162 9 Claims. (Cl. 103-50) ABSTRACT OF THE DISCLOSURE A vertical shaft extends downwardly into a drum from which liquid is to be removed and is reciprocated up and down by alternatingly directing air under pressure to the upper and lower sides of a diaphragm connected to the uppermost end of the shaft. A slidable spool serves as a valve for directing the air, there being a pair of springs that are successively compressed, but not completely, before the spool is shifted from one position to another. A piston is reciprocably and slidably disposed between a tubular casing and the lower portion of the shaft. The shaft actuates the piston upwardly and downwardly to produce the requisite pumping action, the liquid being pumped then being forced upwardly through the shaft itself and out at an elevation above the top of the drum. Provision is made for bypassing some or all of the liquid back into the drum. An agitator is oscillated by the shaft as the shaft reciprocates vertically so as to stir the liquid in the drum. Also, means are provided for diverting some of the air as it is exhausted in a direction so that the liquid being pumped does not congeal or harden around the shaft where it is otherwise likely to congeal or harden.

BACKGROUND OF THE INVENTION Field of the invention Description of the prior art While pumps have heretofore been designed for removing liquids from drums and barrels, the pumping portion of the unit has not been of a type so as to be inserted through the bunghole and thus be located near the bottom of the drum. It is exceedingly desirable that the pumping take place as low in the drum as possible in order to provide a constant head which eliminates any need for priming. Also, where liquids are to be pumped that are viscous and abrasive, paint being in this category, special problems arise with respect to any use of check valves, sealing rings and the like. Furthermore, where the liquid is abrasive, it must be constantly agitated in order to eliminate settling. Frequently, some of the liquid, especially to prevent settling, must be returned to the drum. Still further, clogging at vulnerable locations has occurred in the past. Yet another disadvantage with pumps that have been available heretofore resides in the fact that they have had to be constructed with fairly close tolerances, thereby contributing to an excessive amount of wear, particularly when pumping viscous and abrasive liquids.

SUMMARY OF THE INVENTION The present invention involves the utilization of several casing sections that can be threadedly secured together so that liquids can be pumped from drums or barrels of different sizes. For instance, the pump constructed in accordance with the teachings of the present invention can be used to pump from a 5, 16, 30 or 55 gallon drum. A

single shaft, also composed of sections coupled together, extends downwardly through the casing which is of tubular form so that the lower end of the shaft can be employed in the actual pumping operation, whereas the upper portion of the shaft cooperates in directing the air to either the upper or lower side of the diaphragm which serves as the motor for the device. By having the shaft extend into a proximal relationship with the bottom of the drum, the shaft is used as the actuating means for an agitator which can be inserted through the bunghole of the drum as the device is being installed thereon for the pumping operation. A cam follower that is moved in unison with the shaft causes the agitator to oscillate and thereby keep the contents of the drum stirred during the removal thereof. Provision is also made for returning any desired portion of the pumped liquid back to the interior of the drum even though the liquid being pumped is discharged at a location above the top of the drum. Air is introduced into the device above the drum and is also discharged above the drum, although a portion of the discharged air is directed downwardly so that it exits adjacent the outlet so as to prevent clogging in this otherwise vulnerable location which is otherwise apt to take place when the device is shut down.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a front elevational view of my device showing it actually mounted for pumping liquid from a drum;

FIGURE 2 is a perspective view of the portion of my device extending above the top of the drum and also illustrating a spray gun attached thereto;

FIGURE 3 is a vertical sectional view taken in the direction of line 33, the shaft being moved upwardly in this view;

FIGURE 4 is a sectional view corresponding to FIG- URE 3 but with the shaft moving downwardly;

FIGURE 5 is an enlarged fragmentary sectional view illustrating the shaft as it moves in FIGURE 3 but showing the spool and upper portion of the shaft in cross section in order to depict to better advantage the flow of air;

FIGURE 6 is a fragmentary sectional view like FIG- URE 5 but corresponding to the direction of shaft movement appearing in FIGURE 4;

FIGURE 7 is a sectional view taken in the direction of line 7-7 of FIGURE 4 for the purpose of illustrating a longitudinal passage that diverts some of the outlet air downwardly to a vantage location that assists in the prevention of clogging when the device is to be inactivated;

FIGURE 8 is a sectional view in the direction of line 88 of FIGURE 6, the view showing the downwardly extending passage appearing in FIGURE 7 and its connection with one of the air outlet passages, and

FIGURE 9 is a sectional view in the direction of line 99 of FIGURE 1 in order to illustrate the agitator and the manner in which it is oscillated.

DESCRIPTION OF THE PREFERRED EMBODIMENT Inasmuch as my invention will find especial utility in the pumping of liquids from drums, a typical drum 10 has been pictured in FIGURE 1, having a top 12 and a bottom 14. As is conventional, drums of this type are provided with threaded bungholes 16 which are normally closed by means of a threaded plug. Since it is contemplated that my device will be exceptionally advantageous for the pumping of viscous and abrasive liquids, paint which has both of these characteristics has been labeled 18 in FIGURE 1.

The pumping device or unit exemplifying my invention hasbeen designatedin its entirety by the reference numeral 20. The. device includes a tubular casing 22 comprised of several threadedly connected sections 22a, 22b and 220. As the description progresses, it will become apparent that any preferred number of sections can make up the casing 22 depending upon the size of the drum 10. For instance, when a relatively large drum, say, a 55 gallon one, is the container for the liquid to be removed, then a greater number of sections will be employed than when a relatively small drum, say, a five gallon one, is encountered, or the section 22b may be made in different lengths. As can be discerned from FIGURES 1, 3 and 4, a drum nut 24 is carried by the threads used to connect the casing section 22a to the section 22b. The nut 24 engages the threaded bunghole 16. Anchored to the upper end'of the casing 22 is a housing 26 having therein a flexible diaphragm 28 with confronting retaining discs 30. The diaphragm 28 divides the interior of the housing 26 into an upper chamber 32 and a lower chamber 34.

As best seen in the various sectional views, more specifically, FIGURES 3 4, 5, 6 and 8, there is an air inlet 36 in the upper casing section 22a. Also provided in this same casing section is a plurality of upper air outlets 38 and a plurality of lower air outlets 40.

Reciprocably disposed in the upper casing section 22a is a slidable spool 42 that functions as a valve member. The spool 42 has formed therein a pair of vertically spaced circumferential grooves 44 and 46. The upper groove 44 has a plurality of passages 48 extending upwardly therefrom, and the lower groove 46 has a plurality of passages 50 leading downwardly therefrom. The spool 42 is counterbored to form a pair of inwardly projecting flanges 52, 53 intermediate its ends. The passages 48 and 50, as well as the flanges 52 and 53, can be seen in FIGURES 5, 6 and 7. In this way, a volumetrically variable space 54 exists above the spool 42 which is in direct communication with the lower chamber 34 beneath the diaphragm 28, whereas a volumetrically variable space 56 exists below the spool.

Of extreme importance in the practicing of the present invention is a shaft 58 comprised of sections 58a, 58b and 58c. It will be recalled that the casing 22 is composed of sections and the same number of shaft sections are employed as casing sections. The upper end of the shaft 58 is externally threaded at 60. Through the agency of a pair of diaphragm nuts 62, 64, the shaft 58 is mechanically coupled or attached to the diaphragm 28 and is in this way forced up and down as the diaphragm flexes. Within the shaft 58 is a longitudinal passage 66 that communicates with the chamber 32 above the diaphragm 38. The passage 66 leads downwardly and connects with transverse passages 68 which in .turn establish communication with the space 56 beneath the spool 42.

The specific reason for the inwardly projecting flanges 52, 53 will now become clear, it is believed. An upper coil spring 70 has its lower end abutting the flange 52 and a lower coil spring 72 has its upper end abutting the flange 53. The upper spring 70 bears against the nut 64 and the lower spring bears against a shoulder 73 integral with the shaft 58.

Playing an important role in the shifting of the spool 42 is a detent mechanism comprised of a ball 74 which is biased or urged inwardly by a spring 76, there being a plug 78 that retains the spring in place. The ball 74 will project into either the upper groove 44 or the lower groove 46 formed in the spool 42 as already explained. The ball 74 will release the spool so as to allow it to move upwardly or downwardly, as the case may be, the spool being limited in its upward movement by a stop 80 in the form of a circular flange and limited in its downward movement by a lower stop 82 in the form of a set screw. A comparison of FIGURES and 6 will reveal that neither coil spring 80 or 72 becomes fully compressed when these limits or stops are struck, the reason for which will become apparent when considering the operation of my device. The detent mechanism is best understood from FIGURES 5 and 6. An O-ring 84 is confined between the flanges 52 and 53, and thus seals the counterbore above the flange 52 from the counterbore below the flange 53; in actual practice, either of the flanges would be in the form of a ring pressfitted against a shoulder (not shown) so as to facilitate insertion of the O-ring 84.

It has already been mentioned that the shaft 58 includes sections 58a, 58b and 580. The sections 58a and 58b are connected together by a transverse pin 88 and the sections 58b, 58c together by a pin 90.

The paint 18 is discharged via an outlet 92 in the shaft 58, being allowed to move upwardly and downwardly relative to the casing 22 by reason of a vertically disposed slot 94 in the casing section 22a. In order to afford a path for the pumped liquid 18, a passage 96a is formedin the shaft section 58a, a passage 96b in the section 58b,

and a passage 96c in the section 580. Particular attention is now directed to the division of the passage 96c by a partition 98 which forms passage portions 96c and 960'. The lower end of the passage portion 96c" connects with what will be termed an inlet 100 at the bottom of the shaft. In other words, this inlet 100 is where the paint 18 is drawn into the device by the reciprocal movement of the shaft 58. The liquid as it progresses upwardly after entering the inlet 100 will exit through what will be called intake ports 102 and 104, whereas the liquid thereafter will re-enter the shaft 58 through an outlet port 106. The intake ports are located in association with the passage portion 960" and the outlet port with the passage portion 960. A reciprocable piston 108 is slidably received in the casing section 220, having an upper internal groove 110 and a lower internal groove 112. Also formed in the piston 108 are upwardly directed passages 114 and downwardly directed passages 116; the upwardly directed passages 114 lead from the groove 110, whereas the passages 116 lead from the goove 112. In this way, an upper pumping chamber 118 is formed above the piston 108, the upper end thereof being defined by an annular wall means 120. The downwardly directed passages 116 communicate with a lower pumping chamber 122 defined by a lower annular wall means 124. The up and down sliding movement of the piston 108 is restricted, being limited by upper and lower split rings 126 and 128 which are disposed in circumferential grooves formed in the shaft section 58c.

Since it is intended that my device will be utilized in the pumping of abrasive liquids, as well as viscous ones, an agitator arm 132 is mounted at the lower end of the device. It is pivotally supported on a clevis or hinge 134 by means of a hinge pin 136. The clevis 134 has integral therewith a shank 138 that is contained in a bushing 140. The shank 138 is retained in place by a spring pin 142. Carried on the clevis 134 is a cam follower 144 which is actuated by a cam 146 having a helical slot 148 therein. The cam 146 is in turn disposed within a cam housing 150 which is held in a fixed relation by a retainer 152. The lower end of the retainer 152 provides an inlet 154 so that the liquid 18 can be admitted to the inlet 100 at the bottom of the shaft 58.

Surmounted on the housing 26 is a surge tank 156, as can be seen in FIGURES 1 and 2, there being a flexible hose 158 leading from the outlet 92. The hose 158 connects with a T 160. The paint 18 is then directed in either of two paths, one path being through a flexible hose 162 leading into the surge tank 156. The outlet from the tank 156 is in the form of a hose 164 and is connected to a spray gun 166; for the sake of drafting simplicity, the atomizing hose normally employed when operating the spray gun 166 has been omitted. The other path that the liquid can follow is through a bypass valve 168 which is connected directly with the bypass return inlet 170 located in the upper casing section 22a. As can be discerned from either FIGURE 3 or FIGURE 4, a vertical passage 172 in the casing section 22a extends downwardly into communication with a space 174 existing between the casing section 22b and the shaft section 58!). From there, the

bypassed liquid can exit back into the drum through passages 176 formed in the previously mentioned annular wall means 120 and fixedly aligned discharge ports 177 in the casing section 220.

At this point, specific attention is directed to FIGURES 7 and 8 in which a vertical passage 178 appears. From FIGURE 7, it will be appreciated that the passage 178 extends downwardly and makes connection with a horizontal passage 180 leading inwardly. The horizontal passage 180 is blocked as far as its outward end is concerned by a plug 182. The passage 180 is located somewhat below the outlet 92. A pair of circumferential grooves 184 and 186 repeatedly pass by the horizontal passage 180 when the shaft 58 is reciprocated vertically so that some of the air that would otherwise pass out through the outlets 38 and 40 instead escapes in the vulnerable vicinity of said outlet 92. This, literally speaking, allows the liquid 18 that might otherwise collect in this region to be blown away and thereby prevents it from congealing or hardening; this is particularly advantageous when the device is to be shut down after a pumping operation, for the liquid, more specifically, paint, will not interfere and harden so that subsequent clogging results.

Assuming now that my pump device is to be installed on the drum 10, the plug normally sealing the bunghole 16 is first removed. The device 20, being quite lightweight, can be easily handled by the user. Accordingly, the entire device 20 is tilted so that the agitator arm 132 may be inserted downwardly through the bunghole 16. As the device 20 is lowered, the agitator arm 132, owing to the viscosity of the paint 18, will angle upwardly, somewhat as illustrated in phantom outline in FIGURE 1. It makes no difference whether the drum 10 is full or only partially full as depicted in FIGURE 2. The device 20 should be placed in operation as it is lowered. When operating, the oscillatory movement imparted to the agitator arm 132 (as indicated in FIGURE 9 by the extreme angular positions shown in phantom outline) will, in effect, cause the arm 132 to bore downwardly in the now unmixed paint. With the bypass valve 168, the entire amount of liquid can be returned to the drum 10 so that it is thoroughly mixed before it is sprayed with the gun 166.

The air and paint flow can be most readily traced, it is believed, by applying sequential arrows to the various views. With this in mind, it will be discerned that the air supplied to the device 20 is indicated by the arrow 188, entering via the air inlet 36. In FIGURES 3 and 5, the shaft 58 is moving upwardly. At this point, the spool 42 is retained in the position illustrated in FIGURES 3 and 5 by reason of the ball 74 being in engagement with a segmental portion of the groove 44. Another segmental portion of the groove 44 is in registry with the air inlet 36. Therefore, the air indicated by the arrow .188 is allowed to pass upwardly through the passages 48 of the spool 42. The air is then introduced directly into the lower chamber 34 under the diaphragm 28 as evidenced by the arrows 190. It is the air under the diaphragm 28 that is urging the shaft 58 upwardly. However, the ball 74 keeps the spool 42 from moving upwardly at this time. Of course, the lower coil spring 72, which is confined between the shoulder 73 and the flange 53, is being progressively compressed. Ultimately, the shoulder 73 will strike the lower end of the spool 42 which gives it suflicient upward impetus so as to force the ball 74 outwardly against its spring 76. Since the coil spring 72 has been compressed to an appreciable degree by the time the shoulder .73 engages the spool 42, sufiicient energy has been stored therein which will shift the spool 42 upwardly to such an extent that the groove 46 will then be brought into registry with the air inlet 36.

While the foregoing is taking place, owing to the upward movement of the diaphragm 28, air that is in the upper chamber 32 is forced outwardly as indicated by the arrow 192. The air flows downwardly through the longitudinal passage 66, the air within this passage being indicated by the reference numeral 194. When the downwardly flowing air being exhausted from the upper chamber 32 reaches the transverse passages 68, it flows outwardly as indicated by the arrows 196. It is then between the shaft 58 and the tubular casing 22, more specifically, the upper section 22a. From this region, the air can then flow upwardly through the passages 50 in the spool 42 and then into the groove 46 which is in registry with the lower air outlet 40.

While the major portion of the air is exhausted or discharged via the outlets 40, some of the air is directed downwardly through the vertical passage 178 formed in the upper casing section 22a and then inwardly through the horizontal passage 180. The circumferential grooves 184, 186 repeatedly pass by the inner end of the passage 180 so as to receive air supplied via this route. It is this air that assures that a cleaning action occurs adjacent the liquid outlet tube 92.

While the above-mentioned air paths are being followed, paint 18 is being drawn in at the bottom of the device through the inlet 154 as designated by the arrow 198. The paint moves upwardly as indicated by the arrow 280. Since the piston 108 is being moved upwardly by the shaft 58, the lower split ring 128 actually pulling the piston 108 upwardly, the liquid is drawn into the lower pumping chamber 122 .as indicated by the arrows 202. In other words, the piston 108 is producing a region of reduced pressure by its upward movement which draws paint into the lower pumping chamber 122 through the inlet port 104, the groove 112 of the piston 108 being at this time in registry with the port 104.

Assuming for the moment that paint 18 is contained in the upper pumping chamber 118, the same upward movement of the piston 108 forces this paint downwardly as evidenced by the arrows 204. The groove of the piston 108 is at this time in alignment with the outlet port 106 so that the liquid path is through the port 106 into the portion 960' of the passage 96c. The liquid is at this stage represented by the reference numeral 206. The paint then follows an upwardly directed course as indicated by the arrows 208 and is then discharged through the outlet tube 92 as indicated by the reference numeral 210. The outlet tube 92, as can be seen from FIGURES l and 2, is connected directly to the flexible tube 158.

Since, for the sake of discussion, we can consider the paint 18 within the drum 10 to require mixing, the bypass valve .168 will be open so that the paint will be returned to the drum 10. Therefore, the bypass return 170 carries the liquid and the liquid flow at this point has been indicated by the arrow 212. The passage 172 and the space 174 function to direct the flow of bypassed paint downwardly as designated by the arrows 214. As already pointed out, the annular wall has passages 176 therein which allow the paint to be returned to the drum 10 as designated by the arrows 216.

When the bypass valve 168 is closed, or partially closed, then the paint is directed through the flexible tube 162 into the surge tank .156. From the surge tank 156, the paint is conveyed by the tube 164 to the spray gun 176.

The above-presented information has dealt with the upward stroke of the shaft 58. It is when the spol 42 is shifted to its upper position by reason of the engagement of the shoulder 73 with the lower end of said spool that the air flow is changed. The changed air flow is illustrated in FIGURES 4, 6 and 7, the shaft 58 at this time moving downwardly. However, it will be discerned that the air entering the device 20 as represented by the arrow 188 is now passing through the grove 44 of the spool 42 into its passages 50. This air has been labeled with the arrows 218. The continued downward flow of the air has been given the reference numerals 220 as it enters the transverse passages 78. When in the longitudinal passage 66 and passing upwardly therein, the air direction is set forth by the arrow 222. As the air actually enters the upper chamber 32 above the diaphragm 28, the arrows so designating the air have been given the reference numeral 224.

While the air as evidenced by the arrow 224 is being directed into the upper chamber 32, the air in the lower chamber 34 is being forced downwardly in the direction of the arrows 226 through the passages 48 formed in the spool 42 and then through the groove 44 into the upper air outlets 38, the air being discharged as indicated by the arrow 228 (FIGURE 7). Here again, some of the air is diverted downwardly through the passage 178 to perform a cleaning function as already described.

Still assuming that the shaft 58 is moving downwardly, the paint continues to enter the bottom of the device 20 through the inlet 154, passing upwardly in the same fashion as represented by the arrow 200, but instead of being directed into the lower pumping chamber 122 as previously explained, the liquid now goes into the upper pumping chamber 118 as indicated by the reference numeral 230 in FIGURE 4, passing through the intake port 102 through the passages 118 since the groove 112 of the piston 108 is at this time in alignment with said port 102.

While the paint is entering the upper pumping chamber 118 as described above, the paint previously intro duced into the lower chamber 122 is being forced outwardly therefrom as indicated by the arrows 232, passing upwardly through the passages 116 in the piston 108 and then inwardly through the groove 112, this groove being in registry at the moment with the port 106 so that the liquid flows in the direction of the arrow 234. It is at this time that the liquid is within the portion 960' of the passage 96c so that continued flow is in the same direction as previously mentioned arrows 208 and 210. In other words, the paint being pumped is discharged from the tube 92 on both the upward and downward strokes of the shaft 58.

As the shaft 58 reciprocates vertically, the helical slot 148 causes the follower 144 to move up and down, as well as oscillate, thereby assuring continuous stirring of the paint 18 through the agency of the agitator arm 132. As earlier indicated, if the arm 132 is buoyed upwardly, it will work or dig downwardly as the mixing action progresses.

From the description that has been herein given in conjunction with the device 20 as exemplified in the drawings, it will be appreciated, it is believed, that viscous liquid, such as paint, can be pumped directly from a drum. No priming is needed. Furthermore, the clearances between the relatively moving parts are not particularly important and can be quite large, thereby minimizing the need for seals and/or accurate machining. For example, the piston 108 requires no O-rings whatsoever. Any portion of the liquid being pumped can be recirculated so that complete mixing of any solids that may have settled out can be realized without difficulty. Still further, the cleaning action afforded by bleeding some of the air downwardly through the passage 178 so as to have it discharged in an otherwise vulnerable region contributes to the provision of apparatus that will possess especial utility as far as pumping paint is concerned. The entire device is exceptionally rugged. In this regard, specific attention is called to the fact that the coil springs 70, 72 are never fully compressed so that they are apt to break, yet the energy successively and repeatedly stored therein is enough to alternately dislodge the spool 42, the dislodging resulting in the shifting from one air directing position to another. Still another feature that is highly important is that the shaft 58 serves as the conduit medium through which the liquid being pumped is raised and discharged at an elevation above the top of the drum from which the liquid is being withdrawn. Coupled with the foregoing features is the feature that the pumping device is exceptionally lightweight and inexpensive to manufacture.

What is claimed is:

1. A device for pumping liquids from a drum comprising a tubular casing adapted to depend downwardly through the bunghole in the drum, a housing at the upper end of said casing, a flexible diaphragm dividing said housing into upper and lower chambers, shaft means connected at its upper end to said diaphragm and vertically reciprocable in said casing, said shaft means having a first passage therein extending upwardly into said upper chamber from a first location intermediate the ends of said shaft means and having a second passage extending downwardly into said drum from a second location beneath said first location, said casing having an air inlet subjacent said housing, means between said casing and an upper portion of said shaft means shiftable relative to said casing and relative to said shaft means for directing air from said inlet into said first passage to cause air to travel into said upper chamber and thereby force said shaft means downwardly, a reciprocable piston slidably encircling a lower portion of said shaft means, said casing and piston forming a pumping chamber, said piston having a passage communicating with said pumping chamber and said shaft means having a port extending into said second passage of the shaft means in registry with said piston passage, whereby downward movement of said shaft means and said piston causes liquid in said pumping chamber to be forced upwardly through said second passage, said second passage having an outlet at the upper end thereof through which said liquid is discharged.

2. A device in accordance with claim 1 in which said shiftable means alternatively directs air from said inlet into said lower chamber to move said shaft means upwardly, said casing having a pair of vertically disposed outlets, said shifting means causing air to be exhausted from said upper chamber to one of said outlets when air is being directed into said lower chamber and causing air to be exhausted from said lower chamber to the other of said outlets when air is being directed into said upper chamber.

3. A device in accordance with claim 2 in which said casing and piston form a second pumping chamber, said piston having a second passage communicating with said second pumping chamber and registrable with said port, whereby upward movement of said shaft means causes liquid in said second pumping chamber to be forced upwardly through the second passage of said shaft means for discharge through said outlet.

4. A device in accordance with claim 3 including an agitator arm, and means actuated by said shaft means for imparting oscillatory movement to said agitator arm.

5. A device in accordance with claim 4 in which said last-mentioned means includes a cam having a helical slot therein and a cam follower constrained for movement in said slot, said agitator arm being movable with said cam follower so as to derive said oscillatory movement.

6. A device for pumping liquids from a drum comprising a tubular casing adapted to depend downwardly through the bunghole in the drum, a housing at the upper end of said casing, a flexible diaphragm dividing said housing into upper and lower chambers, shaft means connected at its upper end to said diaphragm and extending downwardly in said tubular casing to the bottom thereof, said casing having an inlet subjacent said housing and a pair of vertically spaced outlets, a reciprocable spool slidably encircling an upper portion of said shaft means having a first pair of vertically spaced circumferential grooves, the lower of said grooves being in registry with the lower of said air outlets when the upper of said grooves is in registry with said air inlet and the upper of said grooves being in registry with the upper of said air outlets when the lower of said grooves is in registry with said air inlet, said spool having a first passage leading upwardly from its upper groove into a space between said casing and shaft means which space is in communication with said lower chamber so as to direct air under pressure into said lower chamber to flex said diaphragm upwardly and to pull said shaft means upwardly therewith when said spool is in a first position with said upper groove in registry with said air inlet and said spool having a second passage leading downwardly from its lower groove into a second space between said casing and shaft means, said shaft means having a passage extending upwardly from said second space into said upper chamber so as to direct air under pressure into said upper chamher to flex said diaphragm downwardly and to push said shaft means downwardly therewith when said spool is in a second position with said lower groove in registry with said air inlet, said air outlets being disposed so that the lower groove is in registry with the lower air outlet when said spool is in its said first position and said upper groove is in registry with said upper air outlet when said spool is in its said second position, first coil spring means compressible when said shaft means moves upwardly to urge said spool upwardly, second coil spring means compressible when said shaft means moves downwardly to urge said spool downwardly, detent means for releasably retaining said spool in its first position while said first coil spring means is being compressed to a predetermined extent at which time the detent means releases said spool to move from its said first position to its said second position under the influence of said first spring means and said detent means then releasably retaining said spool in its said second position while said second coil spring means is being compressed to a predetermined extent at which time the detent means releases said spool to move from its said second position back to its said first position under the influence of said second spring means, a reciprocable piston slidably encircling a lower portion of said shaft means, respective wall means above and below said piston extending inwardly to said shaft means to define upper and lower pumping chambers, means projecting from said shaft means at a location above said piston engageable with the upper end of said piston, means projecting from said shaft means at a location below said piston engageable with the lower end of said piston, said respective projecting means determining the pumping stroke of said piston, said piston having upper and lower internal grooves, an upwardly extending passage leading from said upper internal groove into said upper pumping chamber and a downwardly extending passage leading from said lower internal groove into said lower pumping chamber, said lower shaft portion having upper and lower intake ports at one side and an outlet port at the other side, the lower of said internal grooves being in registry with said lower intake port when said piston is in a first position engaging the lower of said projecting means and said upper internal groove being in registry with said upper intake port when said piston is in a second position engaging the upper of said projecting means, said upper internal groove being in registry with said outlet port when said piston is in its said second position, a partition in the interior of said lower shaft portion dividing said interior so that said intake ports communicate only downwardly to the lower open end of said shaft means and said outlet port communicates only upwardly to an upwardly located outlet in said shaft means, said casing having an opening therein so that pumped liquid can be discharged via said outlet.

7. A device in accordance with claim 6 in which said casing includes a bypass return extending downwardly from an upper location above the drum to a location within the drum.

8. A device in accordance with claim 7 in which said wall means above said piston contains at least one passage extending outwardly via which the returned liquid passes into said drum.

9. A device in accordance with claim 8 in which said casing is comprised of upper intermediate and lower sections, the bypass return having an inlet in said upper section and said upper section having a downwardly directed passage through which the liquid being returned flows, said intermediate section also containing a passage leading downwardly, said wall means being in said lower casing section and said lower casing section having an outlet port fixedly aligned with said wall means passage.

References Cited UNITED STATES PATENTS ROBERT M. WALKER, Primary Examiner. 

